List of who received a message to a dynamic distribution group?

I just created a dynamic distribution group in Exchange 2013.  When I run:

$FTE = Get-DynamicDistributionGroup "groupname"

And then run this:

Get-Recipient -RecipientPreviewFilter $FTE.RecipientFilter | out-file c:\group.txt 

It returns the correct mailboxes as members of the group, however at least 1 user did not get the first email that was sent to the group. I have no idea who else did not get it.

How can I figure out who actually got the message?

I have tried get-messagetrackinglog using the messageID, but that did not show the recipients.

I also tried Delivery Reports tab in ECP, it returned nothing at all from the sender.

I ran this:

Get-ExchangeServer | Get-MessageTrackingLog -ResultSize unlimited  -Start “5/31/2016 13:30:00” -End “5/31/2016 14:00:00” -Sender “mysender@mydomain.com” | format-table -wrap -autosize | out-file c:\track.csv

I got some results with that, but it’s a mess to read & still does not give me a simple list of those who actually got the message.

Any other suggestions?

Thx